The tales of diet and medicine behind sick Neanderthal's teeth

Bee Kee Ng, 22 Mar 2017

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When the Neanderthals of El Sidrón Cave in northern Spain died approximately 50, 000 years ago, their hardened dental plaque left from toothaches have contributed to the study of human evolution. The preserved tooth plaque loaded with genetic material provides microbiologists an intriguing glimpse into the diets of the Neanderthals.

In a study led by Laura Weyrich, a palaemicrobiologist at the University of Adelaide in Australia, researchers extracted the ancient DNA and bacteria from the jaws of three Neanderthal individuals, one from Belgium and two from Spain. The results were then described and elaborated.

What do Neanderthals eat?

From the DNA evidence, the Belgian individuals ate a heavily meat-based diet, particularly woolly rhinoceros and wild sheep. On the other hand, the Spanish Neanderthals seemed to have eaten largely vegetable material, including moss, pine nuts and mushrooms, which can usually be found from foraging in a forest.

In fact, the idea that Neanderthals ate both meat and vegetables or self-medicated with plants corresponds to earlier examinations of nitrogen isotopes found in tooth enamel and physical plant jammed between their teeth. Besides, previous research has found that the varied diet in different regions can result in the diverse wear patterns on the Neanderthal’s teeth.

The jaw of a Neanderthal found in Belgium, which provided genetic clues to ancient diets via tooth buildup. Photo credit: Royal Belgian Institute of Nature Sciences/National Geographic

The more surprising finding Weyrich and her team discovered, nevertheless, was the fact that the meat-eaters’ overall microbiomes differed from the vegetarians’. Plus, they varied altogether from the microbial mixtures that live inside modern humans.

Weyrich said, “Using Neanderthals as a model—people who are stuck in one place and limited to the food sources those places provide—we can determine what they were doing that might have caused a change in their microbiome.”

Keith Dobney, the study’s co-author, suggests that comparing post-agricultural biomes with those of the prehistoric people can offer ideas for how to combat modern dietary blights.

“Microbiomes have evolved over millions of years with us, and we can’t live without them,” Dobney said. “Obesity, diabetes—these don’t come out of nowhere. This will give us some serious insight on how changes in migration and diet have impacted human society.”

Prehistoric aspirin and penicillin

Meanwhile, the dental plaque has been previously used to analyse the starches and proteins preserved in the plaque, which indicate the consumption of many plants in the Neanderthals’ diet, possibly in medicinal use as the El Sidrón Neanderthals are claimed to use plants to self-medicate.

Neanderthals ate what was available in their environments, leading to markedly different diets between groups. Photo credit: Mauricio Anton/SPL/ Nature News

Based on the research, one of the Spanish Neanderthals had a dental abscess and the genome of a poplar tree found on the individual’s teeth likely provided salicylic acid, the active ingredient in aspirin, for pain relief. The individual also suffered from diarrhoea and vomiting caused by a different pathogen, Enterocytozoon bieneusi, and may have sought antibiotic-producing moulds for treatment. The genetic material from Penicillium rubens found on plant matter in this individual’s teeth proved the case.

The advent of super high-power microscopy and precision genetics tools has enabled a more in-depth study on the prehistoric plaques, offering an insight of the ancient medication.

Possible interbreeding between Homo sapiens and Neanderthals

Furthermore, Weyrich’s team also sequenced the entire genome of the gum disease-causing Methanobrevibacter oralis, at 48,000 years old, which is thus far the oldest bacterial genome.

Based on genome comparisons, the microbe’s modern lineage was found to be split from the Neanderthals after the hominins’ last common ancestor lived whereas the modern form of this bacterium is transmitted from person to person through saliva. Hence, it shows possibilities of humans and Neanderthals interacting during intimate moments.

A closeup of the Neandertal teeth shows dental calculus deposits as a rind on the tooth enamel. Photo credit: Royal Belgian Institute of Natural Sciences/National Geographic

“If you’re swapping spit between species, there’s kissing going on, or at least food sharing,” said Weyrich, “which would suggest that these interactions were much friendlier and much more intimate than anybody ever possibly imagined.”

Lawrence Straus, an anthropologist at University of New Mexico, said “It would be truly fantastic to see evidence of the passing of specific bacteria from Neanderthals to Homo sapiens.” MIMS

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